Primary coil unit

ABSTRACT

A primary coil unit is configured for electromagnetically coupling with a secondary coil unit. The primary coil unit includes a primary coil and a primary ferrite, where the primary coil is movably supported relative to the primary ferrite.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT International Application No.PCT/EP2017/052136, filed Feb. 1, 2017, which claims priority under 35U.S.C. § 119 from German Patent Application No. 10 2016 205 352.3, filedMar. 31, 2016, the entire disclosures of which are herein expresslyincorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a primary coil unit, which is suitable forelectromagnetically coupling with a secondary coil unit, wherein theprimary coil unit comprises a primary coil and a primary ferrite, and toa method for the supply of electrical components with electric power bymeans of an inductive charging system having a primary coil unit and asecondary coil unit.

Vehicles with an electrically-powered drive typically incorporate abattery, in which electrical energy for the operation of an electricalmachine of the vehicle can be stored. The vehicle battery can be chargedusing electrical energy from a power supply network. To this end, thebattery is coupled to the power supply network, in order to permit thetransmission of electrical energy from the power supply network to thevehicle battery. Coupling can be executed by a wired arrangement (usinga charging cable) and/or by a wireless arrangement (by means ofinductive coupling between a charging station and the vehicle).

One approach to automatic inductive wireless charging of the vehiclebattery involves the transmission of electrical energy to the batteryfrom the road surface to the vehicle underfloor by means of magneticinduction across the underfloor space. To this end, the vehicleincorporates a secondary charging unit, which interacts with anoff-board primary charging unit by means of magnetic coupling.

In the interests of efficient inductive coupling, it is necessary thatlosses in the coils of the primary charging unit and the secondarycharging unit should be maintained as low as possible, and that theposition of the two charging units during charging, in the x directionand the y direction of the vehicle (according to the axis coordinatesystem of a vehicle which is known by a person skilled in the art)should coincide insofar as possible.

According to the prior art, c.f., for example, document US 2010117596A,systems for the accurate positioning of a vehicle on a parking space aretherefore proposed, which incorporate a primary coil unit, in order topermit the achievement of optimum magnetic coupling.

One object of the invention is to provide an improved primary coil unit,which is suitable for electromagnetically coupling with a secondary coilunit, wherein the primary coil unit comprises a primary coil and aprimary ferrite, and to specify an improved method for the supply of anelectrical component with electric power, wherein an inductive chargingsystem having a primary coil unit and a secondary coil unit is employed.

According to the invention, the primary coil is movably supportedrelative to the primary ferrite.

This means that the primary coil unit, which incorporates the primarycoil and the primary ferrite, is configured such that the primary coilis not rigidly connected to the primary ferrite, but is displaceablysupported in relation to the latter.

To this end, according to one form of embodiment of the invention, theprimary coil is preferably configured as a circular coil, wherein theprimary ferrite assumes a planar basic shape, having a first side and asecond side, and the primary ferrite is designed to accommodate theprimary coil in the weight thereof, in a cooperating arrangement withthe first side of said planar basic shape. Other types of coils, whichcan cooperate with the primary ferrite in a stable arrangement, can alsobe employed.

The displaceable arrangement of the primary coil relative to the primaryferrite can thus be achieved, in that the primary ferrite assumes aplanar basic shape, e.g. in the form of an oval, rectangular or circularplate-type design. As a planar design, by definition, essentiallycomprises two sides, reference is made here to the first side and thesecond side. On one of the two sides, described here as the first side,the primary coil, in the intended use of said primary coil, in responseto the weight thereof, preferably engages with the first side of theprimary ferrite, and is movable relative to the primary ferrite, in theplane in which the planar basic shape of the primary ferrite extends. Inother words in the intended use, the primary coil thus exerts themass-related weight force thereof essentially on the first side of theprimary ferrite plate.

The relative movability of the primary coil relates to the plane of theprimary ferrite plate, i.e. if the primary coil moves, a plane-parallelmovement is executed in the direction of extension of the primaryferrite plate, and relative to said primary ferrite plate.

According to a further variant of the invention, the primary coil unitincorporates at least one ferrite element, wherein the at least oneferrite element is movably supported relative to the primary ferrite.

In other words, the primary coil unit, in addition to the primaryferrite, additionally incorporates at least one further ferrite element,which is movably supported relative to the primary ferrite. Accordingly,both the primary coil and the at least one further ferrite element aremovably supported relative to the primary ferrite.

Preferably, the at least one ferrite element is supported relative tothe primary ferrite in a hinged arrangement, wherein the ferrite elementis supported in a fold-out/foldaway arrangement in the plane constitutedby the planar basic shape of the primary ferrite.

Whereas the primary coil is movably supported for displace in the planeof the primary ferrite, the at least one ferrite element can be hingedrelative to the planar basic shape of the primary ferrite. The ferriteelement, upon the hinging thereof, can thus be folded out of the flatplate-type plane of the primary ferrite, or can be folded away into thelatter. In this manner, the magnetically active surface area within theprimary coil unit which, in any event, incorporates the magneticallyactive surface area of the primary ferrite, is reduced or expanded atthe location of the ferrite element. Depending upon the operatingsituation of the primary coil unit, either an expansion or a reductionof the magnetically active surface area of the primary coil unit at thelocation of the ferrite element may be desired. This expansion orreduction can be achieved by the corresponding foldaway or fold-out ofthe ferrite element.

According to a further variant of the invention, the at least oneferrite element incorporates a magnetically non-conductive screeningelement, and said magnetically non-conductive screening element, whenthe ferrite element is folded away, constitutes a continuation of thesecond side of the planar basic shape of the primary ferrite.

The second side of the planar basic shape of the primary ferrite, asdescribed above, is that side of the primary ferrite which lies oppositethe first side of the primary ferrite, with which the primary coilengages in the intended use of the primary coil unit. When ferriteelements are folded away into the plane of the primary ferrite, thescreening elements thus lie in the plane of the primary ferrite, but onthat side of the primary ferrite which is averted from the primary coil.When ferrite elements are folded out of the plane of the primaryferrite, the screening elements are virtually perpendicular to the planeof the primary ferrite. This means that, with a ferrite element foldedout, not only is the magnetically active surface area of the primaryferrite reduced at this location on the relevant ferrite element, butadditionally that the magnetically non-conductive screening elementsuppresses the propagation of stray magnetic fields. Consequently, theseelements not only contribute, in the foldaway position, to theoptimization of magnetic flux behavior in the primary ferrite, but also,in the fold-out position, to the screening of harmful stray fields.

According to an advantageous further development of the invention, theprimary coil unit incorporates a plurality of ferrite elements. Thisplurality of ferrite elements are arranged, relative to the primaryferrite, such that the primary ferrite, along the planar basic shape, isentirely enclosed by ferrite elements.

In this manner it is ensured that, in the flat base plane of the primaryferrite, said primary ferrite is enclosed by foldaway and fold-outferrite elements. In each direction in the plane of the primary ferrite,the magnetically conductive surface area of the primary charging unitcan thus be optionally increased (with the elements folded away) orreduced (with the elements folded out).

According to a further variant of the invention, the plurality offerrite elements comprise groups and sub-groups of ferrite elements,wherein the primary coil unit, for each respective sub-group of ferriteelements, incorporates a suspension device for the constituent ferriteelements of the sub-groups, and one group of ferrite elements comprisesa plurality of sub-groups of ferrite elements, wherein the primary coilunit, for each respective group of ferrite elements, comprises a ferriteelement control unit, by means of which the respective suspensiondevices of the constituent sub-groups of ferrite elements in the groupare controllable, in order to foldaway or fold-out the ferrite elementsin a sub-group.

In other words, not each individual ferrite element needs to beindividually controllable, i.e. able to be folded away or folded out,but a plurality of ferrite elements can be combined in groups andsub-groups, which are hinged in combination. One sub-group of ferriteelements is arranged on the same suspension device, i.e. the entiresub-group can be folded away or folded out. The control unit can controla plurality of such sub-groups, i.e. can execute the mutuallyindependent foldaway or fold-out of the ferrite elements thereof,wherein said plurality of sub-groups constitutes a group, or the entiregroup of ferrite elements is folded away or folded out.

It is essential that the effective magnetic surface area of the primarycoil unit is adjustable by the hinging of the ferrite elements, whereinthe maximum effective magnetic surface area is given by the surface areaof the primary ferrite and the constituent surface areas of all theferrite elements, where the latter are folded away, and the minimumeffective surface area is given by the surface area of the primaryferrite alone. By the hinging of a sub-quantity of ferrite elements, asurface area size setting between these two extreme surface areas can beachieved.

Particularly advantageously, a charging system comprises a primary coilunit of this type and a secondary coil unit, wherein the primary coilunit is suitable for electromagnetically coupling with the secondarycoil unit, such that an electrical component which is connectable on thesecondary side can be supplied with electric power.

The charging system thus comprises, additionally to the primary coilunit according to the invention or the further development thereofaccording to the invention, a secondary coil unit, in order to permitthe transmission of electric power by the electromagnetic coupling ofthe primary coil unit to the secondary coil unit. The secondary coilunit can be a secondary charging unit from the prior art.

A method according to the invention is moreover proposed for the supplyof an electrical component with electric power using an inductivecharging system having a primary coil unit and a secondary coil unit.The method comprises the following steps:

setting a rough position of the secondary coil unit relative to theprimary coil unit, in order to permit the establishment ofelectromagnetic coupling between the primary coil unit and the secondarycoil unit,

displacement of a primary coil in the primary coil unit relative to aprimary ferrite in the primary coil unit in a preferred direction, froma starting position of the primary coil to a charging position of theprimary coil, in order to increase the electromagnetic coupling factorof the rough position of the secondary coil unit relative to the primarycoil unit, wherein the preferred direction lies in the plane of a planarbasic shape of the primary ferrite, and

expansion of the magnetically active surface area of the primarycharging unit in the plane of the planar basic shape of the primaryferrite, in the preferred direction of displacement of the primary coil,in order to further increase the magnetic flux through the primary coiland the secondary coil unit in the charging position, and/or

reduction of the magnetically active surface area of the primarycharging unit in the plane of the planar basic shape of the primaryferrite, against the preferred direction of displacement of the primarycoil, in order to minimize stray fields in the primary coil and thesecondary coil unit in the charging position.

Firstly, in order to permit the transmission of electric power using thecharging system, by the electromagnetic coupling of the primary coilunit to the secondary coil unit, the secondary coil unit is roughlyspatially positioned in relation to the primary coil unit. In a roughposition of this type, which is generally set by the parking of thevehicle, although electromagnetic coupling between the two units can beachieved, the coupling factor in the rough position is not generallyoptimal. In the interests of the optimization thereof, in a furtherstep, the primary coil of the primary coil unit is displaced relative tothe primary ferrite of the primary coil unit along a preferred directionfrom a starting position of the primary coil to a charging position ofthe primary coil.

This displacement can be achieved by one of a number of possiblemeasures, or by a combination of a plurality of said measures. Aninteractive magnetic arrangement is conceivable between magnetic fieldsgenerated for the positioning process, in the form of primary- andsecondary-side positioning coils. The primary and secondary coilsthemselves can be deliberately employed for this purpose too.Preferably, however, positioning motors, which deliver a displacementforce to the coil by means of cable pulls or connecting rods, areemployed. In order to permit any desired positional setting of theprimary coil in a two-dimensional plane, the integration of twopositioning motors is provided. A planar displacement path of +/−10-20cm, in each direction of the plane, should be permitted.

The setting of the control motors for the positioning of the coils canbe achieved by the setting of a localized maximum value for thetransmission efficiency of electric power between the primary andsecondary coils. In the charging position, the coupling factor isimproved, in comparison with the coupling factor in the rough position.The preferred direction of displacement lies in the plane of the planarbasic shape of the primary ferrite. In a final step, the magnetic fluxof the alternating field for the transmission of electric power isfurther optimized, wherein the magnetically active surface area of theprimary ferrite in the plane of the planar basic shape of the primaryferrite is adapted to the charging position of the primary coil. Theeffective surface area in the region of the charging position is thusincreased, i.e. in the direction in which the displace of the primarycoil has been executed in the preceding step. Additionally, themagnetically active surface area of the primary ferrite can be reduced,in the direction from which the primary coil has been displaced in thepreceding step. In this manner, the magnetic flux in the primary ferriteis suppressed at those locations in which said flux is ineffective forthe purposes of power transmission. In other words, a magneticallyactive surface area can be adjusted by the hinging of the ferrite suchthat, in the charging position, the primary coil is centered on amagnetically active surface, i.e. the coil and the surface areaconstituted by hinging share a common geometrical center point in theplane of the primary ferrite.

According to a further development of the method for the supply of anelectrical component with electric power using an inductive chargingsystem having the primary coil unit and the secondary coil unit, thefollowing steps are executed:

setting a rough position of the secondary coil unit relative to theprimary coil unit, in order to establish electromagnetic couplingbetween the primary coil unit and the secondary coil unit,

displacement of the primary coil relative to the primary ferrite in apreferred direction, from a starting position to a charging position,wherein the preferred direction lies in the plane of the planar basicshape of the primary ferrite, in order to increase the electromagneticcoupling factor of the rough position of the secondary coil unitrelative to the primary coil unit,

fold-out of ferrite elements which are initially folded away, relativeto the primary ferrite, by the actuation of one or more ferrite elementcontrol units, wherein those ferrite elements are folded out which, inthe charging position, are arranged with the largest clearance to theprimary coil, and/or foldaway of ferrite elements which are initiallyfolded out, relative to the primary ferrite, by the actuation of one ormore ferrite element control units, wherein those ferrite elements arefolded away which, in the charging position, are arranged with thesmallest clearance to the primary coil, such that a magnetically activesurface area is constituted, upon which the primary coil, in thecharging position and in the viewing direction, is centeredperpendicularly to the plane of the planar basic shape of the primaryferrite.

According to this method, for the purposes of the enlargement and/orreduction of the magnetically active surface area of the primaryferrite, ferrite elements in the plane of the planar basic shape of theprimary ferrite are folded away or folded out. For the optimumtransmission of power and energy, those ferrite elements are or remainfolded away which, in the region of the charging position, into whichthe primary coil has been displaced in the preceding step, are locatedin the plane of the primary ferrite. Those ferrite elements which arearranged with a greater spatial clearance from this charging positionare or remain folded out. By the targeted fold-out or foldaway offerrite elements, a magnetically active surface area is constituted,upon which the primary coil is centered, i.e. the primary coil, in theviewing direction, is centered on the primary ferrite, perpendicularlyto the plane of the planar basic shape of the primary ferrite. As aresult of the preceding process step, in this viewing direction, thesecondary coil is likewise centered on the magnetically activeprimary-side surface, and is thus also centered on the primary coil.Consequently, the magnetic flux conducted in the magnetically activesurface area is concentrated at that location in which the primary coilis also located, such that the maximum permeation of the primary coiland the secondary coil by the alternating magnetic field for thetransmission of power is achieved.

The invention is based upon the following considerations:

Vehicles with an electrically-powered drive system typically incorporatea battery, in which electrical energy for the operation of an electricalmachine of the vehicle can be stored. The vehicle battery can be chargedusing electrical energy from a power supply network. To this end, thebattery is coupled to the power supply network, in order to permit thetransmission of electrical energy from the power supply network to thevehicle battery. Coupling can be executed by a wired arrangement (usinga charging cable) and/or by a wireless arrangement (by means ofinductive coupling between a charging station and the vehicle).

In addition to cabled charging, the wireless inductive charging ofelectric and plug-in hybrid vehicles constitutes a further variant ofcharging, which is characterized by a high degree of convenience and istherefore considered as an attractive option for the end user.

State-of-the-art charging, in the case of inductive charging, proceedssubstantially automatically. Energy transmission occurs over arelatively wide air gap at the vehicle underfloor, in the z-direction,by means of the inductive coupling of an off-board primary coil with anin-vehicle secondary coil. The two coils in combination constitute adetachably-coupled transmission device. The wide air gap which,particularly in the case of off-road vehicle models, can reach highvalues (values in excess of 20 cm in the z-direction of the vehicle),can be critical to energy transmission. Additionally, horizontaldisplacements in the x- and y-directions of the vehicle also occur,since a parking procedure for the positioning of the two coilsrelatively to each other can only be executed with a finite degree ofaccuracy. The objective of current systems is to achieve the maximumpossible tolerance with respect to any offset in the x- and/ory-direction, such that parking up for the end user, i.e. the mutualpositioning of the coils, can be achieved in a simple, rapid andconvenient manner.

Without loss of generality, circular coil units are assumed, customarilyin an essentially quadratic design arrangement. The coil units arerespectively comprised of the actual coil itself and a ferrite. In manycases, the coil winding is configured such that the winding is simply“applied” to the planar ferrite; however, more complex 3D structures arealso possible in which, e.g. the coil is enclosed by the ferrite in aspace-saving arrangement.

Coil systems according to the prior art have a disadvantage in that,where a vehicle is parked with an offset to a stationary floor-mountedprimary coil (offset in the x- and y-direction), a field characteristicis produced wherein, as a result of the lateral offset, only a limitednumber of field lines “flow through” the secondary coil. This results ina reduced coupling factor of the detachably-coupled transmission device,and thus a reduced efficiency of energy transmission; electromagneticlosses are high. According to the prior art, the means whereby a personskilled in the art endeavors to resolve this issue involve the astuteactuation of coils, such that losses in relation to the quantity ofenergy which can still be transmitted are minimized, in order topositively influence the efficiency of transmission with a reducedoverall transmission capacity. Approaches are also known, whereby ax-y-offset is corrected, for example by the displacement of theprimary-side coil unit as a whole—see, for example, DE 102011077427 A1.However, if the entire primary coil unit is tracked, this would involvethe movement of a very large and heavy unit. A complex mechanism isrequired in consequence, which must additionally satisfy the requirementfor overrun limit protection.

An improved technical solution for the management of the x-y-offset istherefore proposed. An approach is selected, wherein only elements ofthe primary coil unit are displaced. Only the winding of the primarycoil is displaced relative to the ferrite, such that the field can bevirtually optimally adjusted to the secondary coil (which is offset as aresult of an inaccurately parked vehicle). Displacement is relativelyeasy to achieve, as the winding of the primary coil rests on theferrite, the copper winding, e.g. in combination with a plastic carrier,has a very low weight and is configured with relatively smalldimensions. The coupling factor associated with a primary coil windingwhich is displaced relative to the ferrite of the primary coil andrelative to the secondary coil approximates closely to that of a systemwith an ideally-positioned secondary coil. Displacement can be achievedby means of positioning motors.

A further option for optimization is however provided in that thehorizontal “range” of magnetic control in the direction of displacementof the primary coil winding is adapted to the edges of the primaryferrite, without the necessity for the movement of the large and heavyprimary ferrite as a whole. To this end, elements of the ferrite arefolded out or folded away. In the edge region, the primary ferrite isthus segmented into individual ferrite elements. Accordingly, by thefold-out and foldaway of elements, magnetic conductivity can beestablished in a preferred direction, and suppressed in otherdirections. Additionally, the ferrite elements can be equipped withscreening plates of non-magnetically-conductive metallic materials, inorder to minimize any stray fields in the fold-out state. Any“bypassing” of the interspaces between one ferrite element and the nextcan also be prevented by the screening effect of the plates. Thefold-out function can also be associated with the positioning motors,which are designed for the displacement of the coil. To this end, thepositioning motors can incorporate such levers as are required to permitthe lever-actuated foldaway of those ferrite elements which lie in thedirection of displacement in a folded-away manner, upon the displacementof the coil, and the lever-actuated fold-out of those ferrite elementswhich lie against the direction of displacement.

At the same time, the interspaces formed by folding-out can be employedfor the insertion of supporting elements between the moving parts, inthe interests of the stability of the primary coil. This is necessary inthe interests of damage-free accessibility to the floor unit in vehiclesof several tons in weight.

The concept envisaged can be applied to other coil designs. It permitsthe horizontal adjustment of the primary coil to a highly inaccuratelyparked vehicle, with no resulting disadvantages in energy transmission.It permits greater tolerance in parking, i.e. in positioning. The systemcan be integrated flush to the road surface (with no projecting triphazards). As only very small and lightweight components are moved,simple implementation is possible. As the field is guided in an optimummanner, electromagnetic emissions are minimized, and electromagneticcompatibility is improved.

According to a further embodiment, the charging system comprised of aprimary and secondary coil is configured in an analogous, butcomplementary manner. This means that the secondary coil is positionedrelative to the primary coil. The hinged ferrites and the positioningmotors are thus also provided on the secondary side. In thisconfiguration, the secondary ferrite, on the gravity load side, isaverted from the secondary coil, such that the secondary coil lies incontact with the secondary ferrite, and essentially engages with alikewise planar housing element of the secondary coil unit, or isinterposed between said housing element and the secondary ferrite.Further technical characteristics can essentially be transferred to thiscomplementary configuration in an analogous manner.

A preferred exemplary embodiment of the invention is describedhereinafter with reference to the attached drawings. Identical technicalelements are identified by the same reference symbols. Further details,preferred forms of embodiment and further developments of the inventionproceed therefrom. Specifically, schematic representations are providedas follows:

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of one ormore preferred embodiments when considered in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a (Prior art) depicts an overhead view of an inductive chargingsystem for the charging of a vehicle.

FIG. 1b (Prior art) depicts a primary charging unit, secondary chargingunit and lines of magnetic flux upon the establishment of theelectromagnetic coupling of a primary coil and a secondary coil in theinductive charging system.

FIG. 2a (Prior art) depicts an overhead view of an inductive chargingsystem for the charging of a vehicle, with the offset positioning of theprimary charging unit and the secondary charging unit during theinductive charging of a vehicle.

FIG. 2b (Prior art) depicts a primary charging unit, secondary chargingunit and lines of magnetic flux upon the establishment of theelectromagnetic coupling of a primary coil and a secondary coil in theinductive charging system, with the primary coil and the secondary coilin an offset position.

FIG. 3 depicts a primary and secondary coil unit with a movable primarycoil.

FIG. 4 depicts a primary and secondary coil unit, with a movable primarycoil and movable ferrite elements.

FIG. 5 depicts a charging system comprising a primary coil unit with amovable primary coil and comprising a secondary coil unit withfolded-out ferrite elements and folded-away ferrite elements.

FIG. 6 depicts an overhead view of the primary coil unit, with anarrangement of foldaway ferrite elements along the periphery of theprimary ferrite.

DETAILED DESCRIPTION OF THE DRAWINGS

According to the prior art, initially FIG. 1a shows an overhead view ofa vehicle (1) in the z-axis, according to the axis coordinate system ofvehicles which is known by a person skilled in the art. The vehicleincorporates a secondary charging unit (3), by means of which thevehicle, using an off-board primary charging unit (2), can beinductively supplied with electric power, preferably for the charging ofan in-vehicle electrical or electrochemical energy store.

For charging purposes, according to FIG. 1b , the secondary chargingunit is positioned at a specific distance in the z-direction (thevertical axis in the spatial reference system). With respect to thex-direction (longitudinal vehicle axis) and the y-direction (transversevehicle axis), the secondary charging unit is ideally to be positionedsuch that, in an overhead view (see FIG. 1a ) an electric coil of thesecondary charging unit (3 a), insofar as possible, is centered on orcoincident with an electric coil of the primary charging unit (2 a). Inthis ideal position, in which the coils are positioned with no lateralx-y-offset, electromagnetic coupling between the two coils for thepurposes of energy transmission is generally optimal. Only thez-direction then influences the degree to which the magnetic field linesof the primary field (10) permeate the secondary coil, such thatelectric power is inducible on the secondary side. The contribution ofstray fields (11), which do not permeate the secondary coil and do notcontribute to electromagnetic power transmission is ideally minimizedaccordingly. The magnetic flux on both the primary side and thesecondary side of ferrites is employed in a targeted manner, i.e. of oneferrite in the primary charging unit (2 b) and of one ferrite in thesecondary charging unit (3 b), which have a high magnetic conductivity,for the spatial straightening of the magnetic field lines such that theactive component of the alternating magnetic field during charging isincreased, and losses associated with stray magnetic field componentsare minimized.

According to the prior art represented in FIGS. 1a and 1b , a problemfrequently occurs in practice wherein, during the charging of thevehicle, an offset in the x-y-direction of the vehicle must beanticipated in relation to the primary charging unit (c.f. the prior artaccording to FIGS. 2a and 2b ), as ideal positioning according to FIGS.1a and 1b cannot be achieved in a controlled manner. In consequence, thestray field component which, according to FIG. 2b , does not contributeto charging, is increased in comparison with the situation representedin FIG. 1b , such that, in general, the at least theoreticallyachievable charging capacity cannot be achieved in practice, or can onlybe achieved with high losses.

FIG. 3 shows one form of embodiment of a primary coil unit (6) accordingto the invention, which overcomes the disadvantage known from the priorart, and incorporates an electric primary coil (6 a) and a primaryferrite of a planar basic shape (6 b). For the transmission ofelectromagnetic power from the primary coil unit to a secondary coilunit (7), which can also be a secondary coil unit having a secondarycoil (7 a) and a secondary ferrite (7 b) from the prior art, aparticularly advantageous arrangement is useful, wherein the primarycoil is displaceably supported relative to the primary ferrite,perpendicularly to the z-axis. The primary coil unit and the secondarycoil unit constitute an inductive charging coil system, wherein thesecondary coil unit is integrated in the vehicle and the primary coilunit is located externally to the vehicle. In the interests of thesimplification of representation, the requisite electronic circuits forthe actuation of the coil units are not represented. If the vehicle isto be charged, for example, i.e. a transmission of power from theprimary side to the secondary side takes place, the vehicle is parked ina rough position relative to the primary coil unit. The offset iscompensated by the subsequent displacement of the primary coil. By meansof the offset, which is detectable using a positioning system of thevehicle relative to the primary coil unit, the optimum charging positionto be set for the primary coil in the x-y-plane of the primary ferriteis established.

For the optimization of the efficiency of electromagnetic powertransmission, the primary coil, in the event of an offset of thesecondary coil relative to the primary coil in the x- and/ory-direction, is displaced from a starting position (represented bybroken lines) to a charging position. The displaced primary coil (6 a′),relative to the secondary coil, a fixed position of which is assumedduring the charging in accordance with the reference system of vehicleaxes which will be known by a person skilled in the art, is ideallyelectromagnetically positioned in relation to the x- and y-axis. Thismeans that, in the charging position of the primary coil,electromagnetic coupling, regardless of any further scope foroptimization with respect to the z-axis, achieves a localized maximumvalue as a function of the relative position of the two coils in the x-and y-direction. This is indicated in FIG. 3 by the magnetic fieldcomponents (magnetic field lines 10) which contribute to powertransmission. In the charging position of the primary coil, stray fieldcomponents are minimized.

FIGS. 4, 5 and 6 show a further form of embodiment of the primary coilunit according to the invention. The primary ferrite is supplemented byferrite elements (21 a to f) of the primary coil unit. The ferriteelements are essentially comprised of the same magnetically conductivematerial as the primary ferrite. Optionally or additionally, the ferriteelements incorporate screening elements (22 a to f), wherein onescreening element respectively is assigned to each ferrite element. Thescreening elements are configured as magnetic screening plates. Theferrite elements are configured, either individually or in groups, in afoldaway or fold-out arrangement in the plane of the primary ferrite,which assumes a planar basic shape. In the folded-away state, theprimary ferrite and the ferrite elements, or the ferrite elements, arearranged in mutual contact. In the folded-away state (c.f. 21 d to f inFIGS. 4 and 5), a direct magnetically-conductive transition thus existsbetween the primary ferrite and the ferrite elements. The magnetic fluxcan thus be conducted, with reduced electromagnetic losses, from theprimary ferrite via the ferrite elements which are folded-away into theplane of the primary ferrite. Where ferrite elements are folded-out ofthis plane (c.f. 21 a to c in FIGS. 4 and 5), magnetic conduction of themagnetic flux from the primary ferrite to the folded-out ferriteelements is suppressed, given that, in the vicinity of the two-foldmaterial transition from the primary ferrite to air and vice versa, andof the screening elements which are arranged virtually perpendicularlyto the plane of the primary ferrite, magnetic field lines, in thedirection of propagation of the folded-out ferrite elements, arescreened (c.f. screened stray field line 12).

From the overhead view in FIG. 6, it will be seen that the primarycharging unit incorporates a plurality of ferrite elements (23 a-c, 25a-c, 27 a-c, 29 a-c, 31 a-c, 33 a-c, 35 a-c and, analogously, so forth),arranged along the periphery of the primary ferrite. The ferriteelements (21 a, 23 a, 25 a, 27 a, 29 a, 31 a, 33 a, 35 a) constitute asub-group of ferrite elements, to which one first ferrite suspensiondevice (101) is common. The ferrite suspension device constitutes anaxis, around which the constituent ferrite elements of the sub-group arehinged.

The hinging of ferrite elements is executed by a ferrite elementmechanism (first ferrite element mechanism 100). A second and a thirdferrite suspension device (102, 103) are assigned to the first ferriteelement mechanism, which respectively comprise further sub-groups offerrite elements. The sub-groups of ferrite elements assigned to theferrite element mechanism constitute a group of ferrite elements. Thethree ferrite suspension devices assigned to the first ferrite elementmechanism can be actuated in a mutually independent manner by theferrite element mechanism.

The ferrite element mechanism can hinge the entire group of ferriteelements, by the rotation of the associated ferrite suspension devices,or individual sub-groups of ferrite elements, by the rotation of therelevant individual ferrite suspension device. Along the periphery ofthe primary ferrite, three further ferrite element mechanisms,correspondingly arranged with respect to the first ferrite elementmechanism and functioning accordingly (c.f., for example, second ferriteelement mechanism 120), are located. The second ferrite elementmechanism serves the three ferrite suspension devices (121, 122, 123),which respectively incorporate sub-groups of ferrite elements. Actuationof the ferrite element mechanism can be executed via a mechanicalcoupling with the positioning motors, which are designed for coildisplacement. A fixed assignment of the hinging state of individualferrite sub-groups in relation to the position of the primary coil inthe x-y-plane is possible. Accordingly, hinging can be tripped bydisplacement along the displacement path executed by the positioningmotors of the coil.

According to a further form of embodiment of the invention, all theferrite elements may be individually hinged, i.e. independently of allthe other ferrite elements respectively.

With reference to FIG. 5, an embodiment of the method according to theinvention is described, by means of which an electric power supply isdelivered to an electrical component which is connectable, on thesecondary side, to a charging system comprising a primary coil unit (6)and a secondary coil unit (7).

The secondary coil unit is roughly positioned, relative to the primarycoil unit. In a further step, the primary coil (6 a), relative to theprimary ferrite (6 b), is displaced into the charging position (6 a′).Optionally or additionally, the ferrite elements which establish theoptimum ferrite profile of the displaced primary coil are folded awayinto the plane of the primary ferrite, in order to guide the magneticfield lines of the power-transmitting alternating magnetic field throughthe two coils with the maximum possible reduction of losses. Moreover,the ferrite elements which are arranged with a substantial clearancefrom the displaced primary coil, and do not contribute to the improvedcoupling of the coils, are optionally or additionally folded out of theplane of the primary ferrite, in order to screen out or suppress anystray magnetic fields which transmit no power. It is advantageous if thedisplacement path of the primary coil and the offset of the primary coilunit and the secondary coil unit in the rough position are determined ormonitored prior to the commencement of the positional optimization ofthe primary coil within the primary coil unit. It can thus be determinedwhich ferrite elements need to be hinged, in order to constitute themagnetically active surface by the foldaway or fold-out of ferriteelements whereby the primary coil, in the charging position, will becentered in relation to said surface.

LIST OF REFERENCE SYMBOLS

-   1 Vehicle-   2 Primary charging unit-   2 a Coil of primary charging unit-   2 b Ferrite of primary charging unit-   3 Secondary charging unit-   3 a Coil of secondary charging unit-   3 b Ferrite of secondary charging unit-   6 Primary coil unit-   6 a Primary coil-   6 a′ Displaced primary coil-   6 b Primary ferrite-   7 Secondary coil unit-   7 a Secondary coil-   7 b Secondary ferrite-   10 Magnetic field lines-   11 Stray field lines-   12 Screened stray field line-   21 a-f Respective ferrite elements-   22 a-f Respective screening elements-   23 a-c Respective ferrite elements-   25 a-c Respective ferrite elements-   27 a-c Respective ferrite elements-   29 a-c Respective ferrite elements-   31 a-c Respective ferrite elements-   33 a-c Respective ferrite elements-   35 a-c Respective ferrite elements-   100 First ferrite element mechanism-   101 First ferrite suspension device, associated with the first    ferrite element mechanism-   102 Second ferrite suspension device of the first ferrite element    mechanism-   103 Third ferrite suspension device of the first ferrite element    mechanism-   120 Second ferrite element mechanism-   121 First ferrite suspension device of the second ferrite element    mechanism-   122 Second ferrite suspension device of the second ferrite element    mechanism-   123 Third ferrite suspension device of the second ferrite element    mechanism

The foregoing disclosure has been set forth merely to illustrate theinvention and is not intended to be limiting. Since modifications of thedisclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

What is claimed is:
 1. A primary coil unit configured forelectromagnetically coupling with a secondary coil unit, wherein theprimary coil unit comprises: a primary coil and a primary ferrite,wherein the primary coil is not rigidly connected to the primary ferritesuch that the primary coil is moveable relative to the primary ferritefrom a starting position for the electromagnetically coupling to acharging position for the electromagnetically coupling, wherein theprimary coil unit incorporates a plurality of ferrite elements, whereinthe plurality of ferrite elements are arranged relative to the primaryferrite, such that the primary ferrite, along a periphery of the primaryferrite, is entirely enclosed by the plurality of ferrite elements,wherein the plurality of ferrite elements comprises groups andsub-groups of ferrite elements, wherein the primary coil unit, for eachrespective sub-group of ferrite elements, incorporates a respectiveferrite suspension device for the constituent ferrite elements of thesub-group, and wherein one group of ferrite elements comprises aplurality of sub-groups of ferrite elements, wherein the primary coilunit, for each respective group of ferrite elements, comprises a ferriteelement control unit, by which the respective ferrite suspension devicesof the constituent sub-groups of ferrite elements in the group arecontrollable, in order to fold away or fold out the ferrite elements ina sub-group.
 2. The primary coil unit as claimed in claim 1, wherein theprimary ferrite assumes a planar basic shape, having a first side and asecond side, and wherein the primary ferrite is configured toaccommodate the primary coil in the weight thereof, in a cooperatingarrangement with the first side of the planar basic shape.
 3. Theprimary coil unit as claimed in claim 1, wherein the plurality offerrite elements incorporate a respective magnetically non-conductivescreening element.
 4. The primary coil unit as claimed in claim 1,wherein the primary coil unit is configured to electromagneticallycouple with the secondary coil unit such that an electrical componentconnected on a secondary side, which corresponds to the secondary coil,is supplied with electric power.